U.S. auto sales in May brought the starkest signs yet that gas prices have dramatically shifted the market to smaller cars, as the top-selling Ford F-series truck was dethroned by cars from Toyota and Honda and as General Motors announced it was closing four truck and SUV plants after dismal results.

General Motors said Thursday that a quarter of its U.S. hourly workers are taking the company's latest buyout offers. Automakers are scrambling to cut costs and adjust production plans as U.S. buyers shift away from trucks and SUVs to smaller more fuel-efficient vehicles.

A local strike on Monday at General Motors' Fairfax plant near Kansas City threatens production of one of GM's hottest-selling vehicles, the Chevrolet Malibu, at a time when the industry is struggling because of the sluggish economy.

As auto supplier American Axle enters its second month with much of its union-represented workforce on strike, the impact is spreading beyond General Motors' truck plants and now beginning to affect GM's car production.

While the $1.7 billion that Ford Motor will net on the sale of Jaguar and Land Rover to India's Tata Motors looks paltry compared with what it paid, every bit of cash it gains will help it weather the current economic downturn, industry watchers say.

In one of the most significant shifts of clout in the auto industry, Ford Motor (F) will hand over the keys to its high-class Jaguar and Land Rover brands to an Indian conglomerate that wants to be a high-end player.